This invention concerns arthroplasty, and, more particularly, resides in improved cutting guides and techniques to better assist a surgeon in preparing a bone, for example, to receive an implant.
Whether for primary or revision arthroplasty, cutting guides are typically employed to ensure that the bone saw performs resections corresponding to mating surfaces of the prosthetic component. For example, in a femoral knee replacement, cutting guides or blocks are temporarily secured to the distal end of the femoral shaft, and include slots into which the blade of an oscillating saw is inserted to shape the end of the bone in accordance with corresponding surfaces of the prosthetic element.
In the case of a revision, the procedure is usually more elaborate due to deterioration of the previously prepared surfaces resulting from decomposition of the bone/prosthesis interface, necrosis, and other factors. Cutting blocks are also typically used in revision procedures, though bone deficiency often renders stabilization of the block impossible. In addition, if the cutting block includes a stem, the positioning of the stemmed implant can alter the fit of the final prosthesis relative to the bone. More recently introduced techniques attempt to base the cuts on an intramedullary guide to which additional cutting blocks are mounted. Though such approaches improve bone cutting accuracy, there remains an unacceptable margin of error, the correction of which in some cases requiring a freehand shaping of the bone.
This invention extends and, in certain instances, improves upon, apparatus and methods disclosed and claimed in U.S. Pat. No. 5,716,361, which relates to combination trial/cutting guides, and methods of using the same, in various orthopedic joint situations such as the knee, hip, shoulder, and other areas of the body. The present invention is directed toward apparatus and surgical techniques which augment or supplant certain teachings of the ""361 patent with respect to alternative cutting fixtures and resection accuracy and stability.
One embodiment provides stabilizers which are removably attached to a cutting guide so as to temporarily lengthen the surface against which a saw or other cutting device rests. Another embodiment provides differently shaped saw blades, having curved distal ends and right-angle bends applicable to box cuts of the type associated with cruciate-sacrifice knee-replacement surgery. Methods are also disclosed whereby the box cuts, distal and posterior augment cuts may be approached from a distal perspective, both laterally and medially. A different embodiment provides a trial/cutting guide having flat surfaces as opposed to curved surfaces adapted for articulation within a joint. Yet a further alternative embodiment teaches a device for determining the joint line relative to a tibia using the fibula as reference.